Isolation and identification of a bioflocculant-producing strain and optimisation of cultural conditions via a response surface model |
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Authors: | Mingyan Yang Yuyan Liang Yan Dou Xia Jia Hongrong Che |
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Institution: | 1. School of Environmental Science and Engineering, Chang'an University, Xi'an, People's Republic of China;2. Shaanxi Key Laboratory of Exploration and Comprehensive Utilization of Mineral Resources, Xi'an, People's Republic of Chinayangmingyan67@163.com |
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Abstract: | A bioflocculant-producing strain named MY6-2 was isolated from a mixed activated sludge by a nitrogen-free medium. Based on 16S rDNA sequence, biochemical and morphological characteristics, the strain MY6-2 was identified as Bacillus mucilaginosus. The chemical analysis indicated that the flocculant MY6-2 was mainly composed of extracellular polysaccharide. The result of the composition of the medium showed that MY6-2 was able to generate bioflocculant in a nutrient-poor medium that consisted of 5?g?L?1 sucrose and no nitrogen source. Response surface methodology (RSM) was used to optimise the fermentation condition of MY6-2 for maximum flocculating activity by using central composite design (CCD). Based on the result, the optimum conditions were as follows: 100?mL of broth in a 250?mL Erlenmeyer flask, initial pH 8.0 and inoculum concentration 10%, respectively. The highest flocculating rate of 90% was achieved under these conditions by adding 0.5?mL fermentation supernatant to 95?mL of Kaolin suspension. |
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Keywords: | bioflocculant Bacillus mucilaginosus flocculating rate RSM fermentation conditions |
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